It is known that organic and polymeric materials with large delocalized .pi.-electron systems can exhibit nonlinear optical response, which in many cases is a much larger response than by inorganic substrates.
Thin films of organic or polymeric materials with large second order nonlinearities in combination with silicon-based electronic circuitry have potential as systems for laser modulation and deflection, information control in optical circuitry, and the like.
Other novel processes occurring through third order nonlinearity such as degenerate four-wave mixing, whereby real-time processing of optical fields occurs, have potential utility in such diverse fields as optical communications and integrated circuit fabrication.
There is continuing research effort to develop new nonlinear optical organic systems for prospective novel phenomena and devices adapted for laser frequency conversion, information control in optical circuitry, light valves and optical switches. The potential utility of organic materials with large second order and third order nonlinearities for very high frequency application contrasts with the bandwidth limitations of conventional inorganic electrooptic materials.
Optical devices which have a polymeric nonlinear optical component are described in U.S. Pat. No. 4,767,169 and U.S. Pat. No. 4,865,406.
Other types of organic materials have been developed which have a novel combination of useful properties, such as electrets which are produced by applying a DC voltage to stretched films of polymers such as polyvinyl fluoride, polyvinylidene fluoride, polyvinyl chloride, polyvinylidene fluoride, polyvinyl chloride, polyacrylonitrile, polycarbonate or nylon 11, while maintaining the films at high temperature and then cooling. These films exhibit piezoelectric and pyroelectric properties.
Polymeric electret elements are useful in electroacoustic conversion devices, electro-mechanical conversion devices, pressure-sensitive elements, bimorph elements, microwave-detection devices, image-recording light-sensitive elements, and the like.
Publications of background interest with respect to present invention electret compositions include U.S. Pat. Nos. 2,615,868 and 4,591,465, which describe copolymers of vinylidene cyanide.
There is continuing interest in the development of novel polymeric materials which exhibit improved piezoelectric and pyroelectric properties, and superior moldability and thermal stability.
Accordingly, it is an object of this invention to provide novel polymers which exhibit nonlinear optical and piezoelectric properties.
It is another object of this invention to provide novel thermoplastic polymers and optical media thereof which are characterized by recurring pendant side chains which exhibit nonlinear optical response.
It is a further object of this invention to provide polymeric electret films which exhibit a high longitudinal piezoelectric effect, and which can function as a transducing element in electro-acoustic, electro-mechanic or pressuresensitive conversion devices.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.